Estudio sobre el requerimiento interno de nitrógeno en lechuga (Lactuca sativa)
Keywords:
Demanda nutrimental del cultivo, requerimiento interno de nitrógeno, acumulación de nitratos, nitrógeno total en tejido, crop nutrient demand, internal nitrogen requirement, nitrates accumulation, total nitrogen in vegetable tissue, Demande en nutriment d’une culture, nécessité interne d’azote, accumulation de nitrate, azote total du tissuAbstract
Abstract. The amount of nutrients demanded by a crop is based on the production of biomass and the internal requirement (IR). This is the optimal concentration of the nutrient in total aerial biomass at the moment of the harvest. The aim of this research was to determine the internal nitrogen requirement in a lettuce crop. In order to obtain it, an experiment was carried out under greenhouse conditions. A complete randomized design was adopted, in which four nitrogen concentrations (5, 10, 15 and 20 meq L-1), were evaluated under semi-hidroponic conditions each one with 20 replicates. Samples were taken four times each 15 days to determine the dependent variables fresh weight (Pf), dry matter of the aerial biomass (Ms), leaf area (Af), percentage of nitrogen (N%) and nitrates (Nit) in vegetable tissue. For all the variables a positive tendency with nitrogen concentration of the solution was observed. For the Pf, Ms and Af variables a statistical difference was observed between the treatments 5 and 20 meq L-1, but not between 10, 15 and 20 meq L-1. The data showed a positive tendency between the nitrogen concentration in the solution and N% and nitrate presence in vegetable tissue. Accumulations of nitrates in vegetable tissue didn´t overcome limits established by the European Commission. The value of internal nitrogen requirement was of 113 kg of N ha-1, determined from the concentration of 15 meq L-1.
